Before delving deeper into the topic of radiation transport in neutron star mergers, it is worth reviewing how we currently understand the evolution of these systems, as well as when different physical processes are expected to play an important role. When discussing neutron star merger simulations, we are typically concerned with the evolution of a binary from tens of milliseconds before merger to a few seconds after merger, i.e. from the moment standard post-Newtonian methods can no longer accurately model the gravitational wave signal to the moment when the accretion disk formed during a merger has lost most of its mass. In the late inspiral (\(O(10)\)  orbits before merger), the tidal distortion of a neutron star by its binary companion has a potentially measurable impact on the gravitational wave signal, which can be used to put constraints on the equation of state of neutron stars [1]}, [2]}. The main role of numerical simulations in that regime is to help test and calibrate analytical waveform models used in the analysis of gravitational wave events (e.g. [3]}, [4]}, [5]} for BNS mergers and [6]}, [7]} for NSBH mergers). General relativity, fluid dynamics, and the choice of equation of state are important at that stage, but magnetic fields only impact relatively weak pre-merger electromagnetic signals and neutrinos have practically no impact on the evolution of the system.
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